Using Mfc with Qt modal dialog and main process

Question

I have an Mfc application where I want to open a Qt modal window, while the Mfc application is still running behind.

To start a Qt application from an Mfc, I got the how to there. This page creates a Dll but my solution creates a static library instead.

As for creating a Qt modal window with main application running behind, it looks easy.

My problem is that it looks like that I cannot combined both solution.

The following code starts the Qt window, but I strongly suspect that I am blocking my main thread and main thread is not able to receive events.

void QtMfcFacade::startDevicesConfigurationWizard(HWND hWnd)
{
    QWinWidget win( hWnd );
    win.showCentered();
    DevicesConfigurationWizard devicesConfigurationWizardUI(&win);
    devicesConfigurationWizardUI.exec();
}

exec function is probably blocking main thread

Following solution should not block main thread, but the Qt windows appears only for few miliseconds and disappeared

void QtMfcFacade::startDevicesConfigurationWizard(HWND hWnd)
{
    QWinWidget win( hWnd );
    win.showCentered();
    DevicesConfigurationWizard devicesConfigurationWizardUI(&win);
    devicesConfigurationWizardUI.show();
}

So, the question is, is it possible to use show function instead of exec function?

(This works if I am creating a Dll and calling the Dll in a worker thread from my Mfc application, but I do prefer using static library)

If the Qt window uses resources (such as a dialog template) then you will have to go with the DLL approach. Static libraries can not contain resources. If there are no resource then it should work in a static library when called from a worker thread. — ScottMcP-MVP, Jun 05 '13 at 21:16

score 0 · Accepted Answer · answered Jun 06 '13 at 15:59

I did not read enough the walkthough.

It is said : "Since we want the dialog to be modeless we cannot create the QWinWidget on the stack, since it would be deleted when it leaves the scope, and all its children, including the dialog, would be deleted as well. Instead we create QWinWidget on the heap, using operator new"

So, to make my window non modal while giving control back to main thread, I should do this :

void QtMfcFacade::startDevicesConfigurationWizard(HWND hWnd)
{
    QWinWidget *win = new QWinWidget( hWnd );
    win->showCentered();
    DevicesConfigurationWizard devicesConfigurationWizardUI = new DevicesConfigurationWizard (win);
    devicesConfigurationWizardUI->show();
}

Using Mfc with Qt modal dialog and main process

1 Answers1